DBR comprising GaP, and use thereof in a semiconductor resonant cavity device

Abstract

A special type of Distributed Bragg Reflectors (DBRs) is provided. Semiconductor resonant cavity devices for emitting or absorbing light are also provided. A DBR is provided for reflecting radiation with a wavelength λ includes at least one mirror pair. Each mirror pair comprises a bottom layer and a top layer, the top layer of one mirror pair comprising gallium phosphide (GaP) and having an optical thickness of substantially an odd multiple of λ/4. A resonant cavity device for emitting or absorbing light with a wavelength λ may comprise a first mirror and a second mirror with an active region located therebetween. The second mirror may comprise a stack of DBRs including at least one mirror pair, the mirror pair having at least a top layer and a bottom layer. The top layer is the layer most remote from the first mirror, and this layer is essentially composed of gallium phosphide (GaP) and has an optical thickness of substantially an odd multiple of λ/4. A method of manufacturing a resonant cavity device for emitting or absorbing light with a wavelength λ is also provided.

1 . A conductive or semiconductive Distributed Bragg Reflector for reflecting radiation with a wavelength λ comprising: at least one mirror pair, each mirror pair comprising a bottom layer and a top layer, the top layer of one mirror pair consisting essentially of GaP and having an optical thickness of substantially λ/4 or substantially an odd multiple of λ/4.  
     
     
         2 . A resonant cavity device for emitting or absorbing light with a wavelength λ, comprising: 
 a first mirror,  
 a second mirror, and  
 an active region, the active region located between the first and second mirror,  
 wherein the second mirror comprises a stack of Distributed Bragg Reflectors including at least one mirror pair, the mirror pair comprising at least a top and a bottom layer, the top layer, being most remote from the first mirror, being composed of GaP and having an optical thickness of substantially λ/4 or substantially an odd multiple of λ/4 and being intended to be used as a contact layer.  
 
     
     
         3 . A resonant cavity device according to  claim 2 , wherein the optical thickness of the GaP layer of substantially λ/4 or substantially an odd multiple of λ/4 includes a deviation of at most 15% from that thickness of λ/4.  
     
     
         4 . A resonant cavity device according to  claim 3 , wherein the deviation is between 0% and 10%.  
     
     
         5 . A resonant cavity device according to  claim 3 , wherein the deviation is between 0% and 5%.  
     
     
         6 . A resonant cavity device according to  claim 3 , wherein the deviation is 0%  
     
     
         7 . A resonant cavity device according to  claim 2 , wherein the first mirror comprises a stack of Distributed Bragg Reflectors including pairs of alternating layers.  
     
     
         8 . A resonant cavity device according to  claim 7 , wherein the optical thickness of the layers of the first mirror comprising the stack of Distributed Bragg Reflectors includes a deviation from substantially λ/4 or substantially an odd multiple of λ/4 by at most 15%  
     
     
         9 . A resonant cavity device according to  claim 8 , wherein the deviation is between 0% and 10%.  
     
     
         10 . A resonant cavity device according to  claim 8 , wherein the deviation is between 2% and 3%.  
     
     
         11 . A resonant cavity device according to  claim 7 , wherein the alternating layers in the first mirror are based on n-type doped AlGaAs and/or InAlGaP.  
     
     
         12 . A resonant cavity device according to  claim 3 , wherein the pairs of alternating layers in the first mirror comprises one to fifty pairs of layers.  
     
     
         13 . A resonant cavity device according to  claim 2 , wherein the first mirror comprises a metal film.  
     
     
         14 . A resonant cavity device according to  claim 2 , wherein the cavity comprises InAlGaP of AlGaAs material.  
     
     
         15 . A resonant cavity device according to  claim 2 , wherein the active region comprises a quantum well structure or a bulk active layer.  
     
     
         16 . A resonant cavity device according to  claim 2 , further comprising a supporting substrate on which the first mirror is disposed.  
     
     
         17 . A resonant cavity device according to  claim 16 , wherein the supporting substrate ( 42 ) comprises semiconductor material.  
     
     
         18 . A resonant cavity device according to  claim 17 , wherein the semiconductor material includes GaAs or Ge or GaP.  
     
     
         19 . A resonant cavity device according to  claim 2 , wherein the second mirror includes more than one mirror pair, whereby all layers except the top layer comprise AlGaAs.  
     
     
         20 . A resonant cavity device according to  claim 2 , wherein the GaP top layer is doped with Magnesium and/or Zinc and/or Beryllium.  
     
     
         21 . A method of manufacturing a resonant cavity device for emitting or absorbing light with a wavelength λ, comprising the steps of: 
 providing a supporting substrate having a surface;  
 forming a first mirror on the surface of the supporting substrate; and  
 forming a second mirror with an active region between the first and second mirrors, the second mirror comprising a stack of Distributed Bragg Reflectors including at least one mirror pair, the mirror pair comprising a top and a bottom layer, the top layer being most remote from the first mirror, being essentially composed of GaP and having an optical thickness of substantially λ/4 or substantially an odd multiple of λ/4, and being intended to be used as a contact layer.  
 
     
     
         22 . A method according to  claim 21 , wherein providing a supporting substrate includes providing a semiconductor substrate.  
     
     
         23 . A method according to  claim 22 , wherein providing a semiconductor substrate includes providing a GaAs, Ge or GaP substrate.  
     
     
         24 . A method according to  claim 21 , wherein forming a first mirror includes growing a stack of Distributed Bragg Reflectors including pairs of alternating layers on the substrate.  
     
     
         25 . A method according to  claim 21 , wherein growing the first mirror including a stack of Distributed Bragg Reflectors includes growing layers with an optical thickness which includes a deviation from substantially λ/4 or substantially an odd multiple of λ/4 by at most 15%  
     
     
         26 . A method according to  claim 25 , wherein the deviation is between 0% and 10%.  
     
     
         27 . A method according to  claim 25 , wherein the deviation is between 2% and 3%.  
     
     
         28 . A method according to  claim 21 , wherein forming a second mirror comprising a stack of Distributed Bragg Reflectors with a top layer essentially composed of GaP having an optical thickness of substantially λ/4 or substantially an odd multiple of λ/4 includes providing a top layer with a deviation of at most 15% from that optical thickness of λ/4.  
     
     
         29 . A method according to  claim 28 , wherein the deviation is between 0% and 10%.  
     
     
         30 . A method according to  claim 28 , wherein the deviation is 0%  
     
     
         31 . A method of manufacturing a resonant cavity device for emitting or absorbing light with a wavelength λ, comprising the steps of: 
 providing a supporting substrate;  
 forming a second mirror with an active region between the second mirror and the substrate, the second mirror comprising a stack of Distributed Bragg Reflectors including at least one mirror pair, the mirror pair comprising a top and a bottom layer, the top layer, being most remote from the supporting substrate, being essentially composed of GaP and having an optical thickness of substantially λ/4 or substantially λ/4 or substantially λ/4 or substantially an odd multiple of λ/4, and being intended to be used as a contact layer;  
 separating the active region and the second mirror from the substrate; and  
 transferring the active region and the second mirror onto a device having a first mirror.  
 
     
     
         32 . A method according to  claim 31 , wherein providing a supporting substrate includes providing a semiconductor substrate.  
     
     
         33 . A method according to  claim 32 , wherein providing a semiconductor substrate includes providing a GaAs, Ge or GaP substrate.  
     
     
         34 . A method according to  claim 31 , wherein forming a first mirror includes growing a stack of Distributed Bragg Reflectors including pairs of alternating layers on the substrate.  
     
     
         35 . A method according to  claim 31 , wherein forming a second mirror comprising a stack of Distributed Bragg Reflectors with a top layer essentially composed of GaP having an optical thickness of substantially λ/4 or substantially an odd multiple of λ/4 includes providing a top layer with a deviation of at most 15% from that optical thickness of λ/4.  
     
     
         36 . A method according to  claim 35 , wherein the deviation is between 0% and 10%.  
     
     
         37 . A method according to  claim 35 , wherein the deviation is 0%